The Dyson boss has filed legal proceedings against its German rival

Sir James Dyson has claimed Bosch are the Volkswagen of the vacuum cleaner world as he launched legal action against his German engineering rival.

“We do not understand these assertions by Dyson and we strenuously reject them,” the company (Bosch) said, adding that it was “committed to full disclosure on the energy ratings and broader performance of our vacuum cleaners”

The inventor of the bagless vacuum cleaner alleged that Bosch is duping consumers with misleading energy-efficiency ratings for its machines.

“Bosch has installed control electronics into some of its machines to wrongfully increase energy consumption when in use – to cheat the EU energy label,” Sir James said. “Their behaviour is akin to that seen in the Volkswagen scandal.

“It seems that industry is rife with manufacturers engineering to find their way around tests, rather than engineering better, more efficient technology. This behaviour is seriously misleading customers.”

Sir James has alleged that the AAAA energy rating achieved by some of Bosch’s vacuum cleaner models was achieved during lab tests with a clean bag in use. But sensors within the vacuum cleaner tell the motor to increase energy use from 750W to 1,600W when the bag is full of dirt to maintain performance, which reduces the energy rating to an E or F.

These findings came to light during independent laboratory testing, according to Sir James. ​

Sir James has alleged that the AAAA energy rating achieved by some of Bosch?s vacuum cleaner models was achieved during lab tests

Bosch has denied that its appliances perform differently at home and under lab conditions, saying that “any suggestion to the contrary is grossly misleading”.

“We do not understand these assertions by Dyson and we strenuously reject them,” the company said, adding that it was “committed to full disclosure on the energy ratings and broader performance of our vacuum cleaners”.

“Bosch has capitalised on the EU regulations which permit that a machine is only tested in an empty state,” Dyson, the company, said in a statement. “Consumers purchasing these machines on the basis of their widely advertised stated AAAA rating are being misled.”

Sir James Dyson has called the EU energy labelling regulation 'flawed' Photo: ANDREW CROWLEY FOR THE TELEGRAPH

Dyson has taken legal action over the Bosch machines - issuing proceedings in Germany, Belgium and the Netherlands. If Dyson’s legal challenge is successful, certain models of Bosch vacuum cleaner may need to be recalled.

“The regulators clearly live in a place that looks nothing like the real world and manufacturers are taking advantage”

Sir James Dyson

His company is currently challenging the regulatory process through a judicial review, demanding that machines are tested under “real world conditions”. That ruling is expected by the end of the year.

All of Dyson’s vacuum cleaners operate at below 1,400W but the bestselling models in the UK use motors with half that power. A spokesman for Dyson said that consumers frequently take energy rating labels into account before purchasing a new vacuum cleaner to save money on energy bills.

Last month Sir James said that the world of regulation was “murky” and provided “a smokescreen for manufacturers to hide behind”.

“[There are] fridges tested with no food, vacuum cleaners tested with no dust, and washing machines tested at inaccurate temperatures,” he claimed. “The regulators clearly live in a place that looks nothing like the real world and manufacturers are taking advantage.”

Bosch supplied the engine control systems that VW used to install “defeat devices”, which embroiled the car maker in the diesels emissions-rigging scandal.